Bizarre Roll Cloud or Horizontal Vortex Cloud Filmed Over Texas

This very strange and unusual roll cloud was recently filmed over Texas, it is normally associated with thunderstorms. At the end of this short video you can clearly see that the cloud is moving at a very rapid pace. It was visible in the sky for only 15 minutes. 

Witness Comments
The video of the tube or roll cloud my wife took as it rolled in at sunrise last Monday morning south of Amarillo Texas in Timbercreek Canyon. A friend said that it is a rare occurrence and sometimes called a morning glory cloud. Weird looking cloud looked like aa ocean wave rolling in. It was a horizontal vortex that extended horizon to horizon.